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(a) top view of the detector layout showing twin-slot antennas, CPW, and a GaAs MESFET. Physical dimensions shown in the figure are: , (b) vertical cross section of the GaAs MESFET along the dotted line in (a). While voltages and are swept independently, electrons in regions A and B are in resonance with incident terahertz radiation. The blue arrows indicate directions of coupled terahertz electric fields, and the thick black arrows indicate directions of photoexcited electrons. [(c) and (d)] 3D electromagnetic simulations with horizontally (c) and vertically (d) polarized terahertz radiation.
Polarization dependence of the detector’s response to radiation at . The polarization and power of the incident terahertz radiation was varied by two wire grid polarizers. The solid curve indicates square-law detector response. In this data, postdetection bandwidth , , , , system current responsivity , system .
Magnitudes of detector responses to radiation vs and at . In this data, best figures of merit are found at , , where , , .
(a) Cross sections of the detector responses at for 0.14, 0.24, 0.6, and radiations. Sharp corners of the data are due to the change in the dominant contribution to the photocurrent between regions A and B. Solid curves are fits to the data. (b) Peak positions (corresponding to region A) vs terahertz frequencies. Dotted line was obtained from 1D-Poisson simulations of the device.
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